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Full text of "Metallurgy Of Cast Iron"

COMPARATIVE   FUSIBILITY   OF   FOUNDRY   METALS.     33!
made two_ experiments, charging simultaneously in each case two pigs of equal weight and shape, one being soft, the other hard. It will be observed that in the open-hearth furnace, filled up with a charge just melting down, these two pigs thrown on top of the white hot metal, and in the full head of the furnace, could be closely watched with the aid of blue glass spectacles. In the first experiment I was surprised to find the soft pig melting first. It became soft and could be broken up by the bar, behaving much like a plumber's wiping metal when it is just soft enough to work. This soft pig, when thus crushed, looks like silver, and makes one wish for time and opportunity to study the characteristics of the carbons while in this state. The hard pig, on the contrary, retained its form remarkably well, not disintegrating like the soft one did, the melted portions dropping off like water. Further investigation developed the fact that the soft iron which melted first was about 55 points higher in the total carbon than the hard iron. (The author held that difference in the graphitic and combined carbons would affect results as seen on pages 154 and 329.) Mr. West, in his second paper, will go into this question fully, as he is making extended experiments in this line. The other trial was with two irons of the same brand, shape, and weight. They had very nearly the same manganese, sulphur, phosphorus, and total carbon, but one had twice as much silicon as the other, resulting in 3.37 per-cent. graphite in the soft pig, and only .68 per cent, in the hard white one. In melting these two pigs under exactly the same conditions, the hard one went first. It held its form well, but in melting ran like water, and was melted beforeiron used as a comparative constant to the hard irons throughout the eight heats. It may be stated that drillings for45 s.	i m.	10 s.	45 s.	i m.	15 s.	nil 3os	nn 458